Adult male rats were maintained on the following dietary regimes: full-fed for 28 days (controls); full-fed 21 days followed by no feed for seven days (acutely starved); no feed for seven days followed by 1/4 feed for 14 days (chronically starved); no feed for seven days, 1/4 of the normal diet for 1/4 days, and completes return of feed for seven days (refed). Serum testosterone (T) and dihydrotestosterone (DHT) were measured by radioimmunoassay and testicular delta 5-3 beta-hydroxysteroid-dehydrogenase (3 beta-HSD) activity was measured by a pregnenolone depletion method. Prostate, seminal vesicles and seminal fluid weight, as well as number of epididymal spermatozoa were reduced in all starved groups. Serum androgens and testicular delta 5-3 beta-HSD activity were significantly reduced in acutely and chronically starved rats. After seven days of refeeding, serum levels of T, DHT, as well as testicular 3 beta-HSD activity rose to control values. In addition, the accessory organ weights and number of epididymal spermatozoa followed a similar pattern. These data provide further evidence that starvation results in impaired testicular function which is reversed by refeeding.